Draw-in gripper assembly for drawing-in warp threads

ABSTRACT

A draw-in gripper assembly for drawing warp threads into weaving components including holding means mounted above one another for holding a plurality of warp threads, fed off of a beam, in place, each individual warp thread forming a loop outside of the clamping point of the upper holding means and being held in position by the lower holding means, draw-in gripper means mounted above the lower holding means, slider head means in the gripper means adapted to clamp a warp thread and pull it from the lower holding means during a draw-in stroke of the gripper means, the warp thread, held in a loop in the upper holding means, being released after a short delay, and, due to the length of thread so released, the warp thread is pulled through eye means of a weaving component, and means for releasing the warp thread from the gripper means at the end of the draw-in stroke.

The invention relates to a draw-in gripper assembly for drawing warpthreads into the weaving parts of a loom.

In practice, warp drawing-in processes and associated equipment areknown, which make use of a drawing-in needle with a thread eye thereon,the warp thread being inserted by means of an associated slot. Dependingupon the size of the thread eye fashioned in the heddle and the kind ofwarp material to be drawn-in, the eye and the insertion slot will be ofdifferent designs. Heretofore, a warp was tensioned and the warp endswere held by a clip. Using suitable and known means to separate a threadfrom the multitude of the others, and by slanting the same, it will beinserted into the eye of the draw-in needle. The thread end is removedfrom the clip during the return stroke or return motion, the free end ofthe thread firmly lying on the loom being drawn in a loop-like mannerthrough the eye of the draw-in needle during needle motion. Because ofthe slim dimensions of the draw-in needle, there remains only anextremely small radius for the loop of the thread.

When drawing coarsely structured threads (for instance burling, loop,crimped structures and the like) into the eye of the draw-in needle,difficulties will be encountered on that account. The coarse threadstructure (burling, loops, etc.) hampers plain sliding through the eye,so there will be frequent rupture of the thread. Hence, quite often thestructured warp material may not be drawn-in by the machine when usingthe warp draw-in machines heretofore employed, this time-consuming andcomplex process having to be performed manually.

German Offenlegungsschrift No. 2,318,249, discloses a process andequipment for drawing-in warp threads which allows pulling a short yarnsection through the first set of weaving parts, a projecting end sectionof the yarn being left in front of the parts and a short segment of yarnbeing pulled through the further set of weaving components. The drawbackin this instance is that only short segments of yarns or warp materialsmay be passed through the eyes of the draw-in needles, i.e., warpthreads fed off of looms in finite lengths may not be processed, or onlyin a cumbersome manner.

The present invention is based on this state of affairs, and providesfor the inserting or drawing-in and passing of warp threads of variouskinds, especially of a coarse kind, through the eyes of heddles and dropwires -- in contrast to the conventional draw-in process -- with theleast possible friction of the individual threads against the edges ofthe eyes or of the weaving components. Another goal is to preventformation of thread loops allowing double passage of thread through theeye during drawing-in, and to achieve draw-in of all textile materialswithout thread rupture.

In the invention, a plurality of warps fed off of the loom are held byknown holding devices and arranged one above the other, each single warpthread outside the fastening site at the upper holding devices forming aloop, the end of all warp threads in the lower holding devices beingheld in place, and the warp threads so held are gripped by draw-ingrippers above the fastening sites of the lower holding devices. Thewarp threads are clamped therein by a slider-head and are pulled out ofthe lower holding devices during their draw-in stroke, upon a shortdelay the warp theads held in loops in the upper holding devices arereleased and the length of thread of the warps so released are pulledthrough the eyes of the weaving parts, the thread ends being released bythe draw-in grippers at the end of the draw-in stroke.

In a further embodiment, the invention provides for the design of thedraw-in gripper as a slider in a gripper tube or sheath. Advantageously,the slider is equipped with an exchangeable head at that end facing thewarp thread. The slider head suitably is provided with a clamping slotat its end face. Lastly, the gripper tube or sheath is provided at theheight of the slider head with a gripper groove oblique in the directionof the positioned warp thread. Furthermore, elastic coupling elementsengage the drivers mounted at the drive ends of the slider and grippertube or sheath.

The advantages obtained by the invention are especially that the warpthreads to be pulled into the heddles or drop wires will be clamped attheir ends in the draw-in grippers and that these warps will be pulledinto and through the eyes in their thread or gripper grooves in theposition of rest without formation of loops which might allow thethreads to pass twice through the eyes during the draw-in thereof.Therefore, textile yarn materials of any structure may be drawn into theweaving parts without thread rupture. In comparison with conventionaldraw-in methods, the friction of the wrap threads to be drawn-in at theeyes of the weaving parts will be reduced by more than half. Because theslider head of the draw-in gripper is exchangeable, its material andthickness may be adapted to the particular warp material being drawn-in.Furthermore, the clamping slot in the slider head and the soft-materialdesign of the head allow clamping the warp threads without kinking. Thispermits drawing-in sensitive warp materials such as glass fibers and thelike without thread rupture.

One embodiment is described below and illustrated by the accompanyingdrawings, in which:

FIG. 1 is a side view of a loom feeding a plurality of warp threads heldin the draw-in position by holding devices, with weaving components anddraw-in grippers being mounted in front of the warps,

FIG. 1a is an enlargement of the draw-in gripper of FIG. 1 with anexchangeable and closed slider head,

FIG. 1b is a cross-sectional view through the draw-in gripper of FIG.1a,

FIG. 2 is a view such as FIG. 1 with the draw-in grippers guided througha weaving component and in the gripping position,

FIG. 2a shows the draw-in gripper of FIG. 1a in the gripping positionwith an open slider head,

FIG.3 shows views of FIGS. 1 and 2 with a warp thread released from itsholding devices, and being pulled through the weaving component by thedraw-in gripper, and

FIG. 3a shows the draw-in gripper of FIGS. 1a and 2a in the clampingposition.

The plurality of warps 2, fed off of the loom 1 in FIG. 1, first areguided obliquely to the upper holding devices 3. Each of latter holds asingle warp thread 2 in clamping jaws 4 in such a manner that every warpthread is doubly clamped and forms a loop 5 outside and upwardly of thejaws. Warp threads 2 hanging loosely downwardly from the upper holdingdevices 3 are gripped at their lower ends by the lower holding devices 6or their clamping jaws 7 and are simultaneously held or clamped. Theheddles 8 are mounted immediately behind the vertical plurality of warps2, supported by the heddle-bearing rails 9 and guided by the same. Theeyes 10 in the heddles 8 are located in a plane 11 closely above thelower holding devices 6, the plane at the same time being theoperational plane for the draw-in grippers 12 mounted so as toreciprocate laterally from the heddles 8. The thread support rods 13 aremounted in front of the plurality of warps 2 and also between the latterand the heddles 8 on one hand and between the heddles and the top endsof the draw-in grippers 12 on the other hand.

The draw-in gripper 12, which is in the position of rest, is composed ofa gripper tube or of a gripper sheath 14 inside of which a gripperslider 15 is movably supported and at the end of which a gripper groove16 is provided. At the slider end, there is a slider head 17 secured bya locking or safety device 18 and thus provision is made for anexchangeable slider head made from a suitable hard or soft material,corresponding to the warp material being used (see FIGS. 1a and 1b). Theother end of the gripper slider 15 is equipped with a drive fork 19 bymeans of which the slider may be moved to and fro inside the grippertube or sheath 14. If the draw-in gripper 12 is moved into theoperational position (see the directional arrow), the gripper slider 15,together with its slider head 17, will move in the opposite direction,so that prior to the gripper groove 16 passing through the eye 10, theslider head 17 will release the gripper groove 16 (see also FIGS. 2 and2a). The slider head 17 at its end face is provided with a clamping slot20 (FIG. 1a) permitting the clamping of the thread without kinking itand with the help of which sensitive warp materials such as glass fibersand the like may be drawn-in without being ruptured.

In FIG. 2, the draw-in gripper 12 is moved toward the heddles 8 (see thedirectional arrow), the gripper groove 16 being guided through the eye10 of the heddle 8 nearest to the warp threads 2 vertically clamped bythe two holding devices 3 and 6. The gripper slider 15 remains behind bythe amount of the clamping stroke h, so that the slider head 17 releasesthe gripper groove 16 (see also FIG. 2a) and hooks into the warp thread2. By suitably controlling the two drive forks 19, the clamping stroke hmay be adapted to the particular thicknesses and materials of the warpthreads 2 being drawn-in, i.e., it may be lengthened or shortened insuch a manner.

FIG. 3 shows the draw-in gripper 12 again in its initial position (FIG.1, see directional arrow). In the process, the end of warp thread 2clamped by the slider head 17 into the gripper groove 16 (also see FIG.3a) is pulled through the eye 10 of the heddle 8. Shortly before thereverse stroke of the draw-in gripper 12, the warp thread 2 is releasedby both holding devices 3 and 6, the thread end first being releasedfrom the lower holding device 6. Only thereupon will there be release ofthe warp 2 from the upper holding device 3 (see the dashed line from theloom 1 to the holding device 3), the warp thread first sliding on thethread support rod 13 mounted to the most adjacent heddle 8 to theholding devices 3 and 6 and located beside the plane of the holdingdevices (dashed line). Upon completion of the reverse stroke of thedraw-in gripper 12, the warp thread falls onto the two lower supportrods 13 mounted in front of the holding device 6 and behind the lastheddle 8. The warp thread 2 will be guided in this manner on both threadsupport rods 13. Upon completion of the reverse stroke of the draw-ingripper 12, the thread end then will be released by the slider head 17from the gripper groove 16.

In order to avoid rupture of the draw-in grippers 13, the drive forks19, which are open to one side, are equipped with elastic coupling beams21 (for instance made of rubber, plastics, etc.) coupled to the grippertube or sheath 14 and to the gripper slider 15. Therefore, in case ofdraw-in gripper impact, the gripper may move toward an improperlypositioned heddle.

It will be obvious to those skilled in the art that many modificationsmay be made within the scope of the present invention without departingfrom the spirit thereof, and the invention includes all suchmodifications.

What is claimed is:
 1. A draw-in gripper assembly for drawing warpthreads into weaving components comprisingholding means mounted aboveone another for holding in place a plurality of warp threads fed off ofa beam, each individual warp thread forming a loop outside of theclamping point of the upper holding means and being held in position bythe lower holding means, draw-in gripper means mounted above the lowerholding means, slider head means in said gripper means adapted to clampa warp thread and pull it from said lower holding means during a draw-instroke of said gripper means, said warp thread held in a loop in saidupper holding means being released, after a short delay, and, due to thelength of thread so released, said warp thread is pulled through eyemeans of a weaving component, and means for releasing said warp threadfrom the gripper means at the end of the draw-in stroke.
 2. A draw-ingripper assembly according to claim 1 in which said weaving componentsare heddles.
 3. A draw-in gripper assembly according to claim 1 in whichsaid gripper means comprises slider means adapted to slide in a grippertube.
 4. A draw-in gripper assembly according to claim 3 in which saidslider means has an exchangeable slider head means at the end thereoffacing a warp thread.
 5. A draw-in gripper assembly according to claim 3including elastic coupling beam means mounted at the drive end of saidassembly in engagement with drive fork means mounted on said slidermeans and said gripper tube.
 6. A draw-in gripper assembly according toclaim 1 including clamping slot means at the end face of said sliderhead means.
 7. A draw-in gripper assembly according to claim 1 includinggripper groove means in said draw-in gripper means at the elevation ofsaid slider head means, said gripper groove means being oblique withrespect to the direction of the positioned wrap thread.